Neutral Particle Transport in Plasma Edge Using Transmission/Escape Probability (TEP) Method

Neutral Particle Transport in Plasma Edge Using Transmission/Escape Probability (TEP) Method

Author: Dingkang Zhang

Publisher:

Published: 2005

Total Pages:

ISBN-13:

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Neutral particles play an important role on the performance of tokamak plasmas. In this dissertation, the original TEP methodology has been extended to take into account linearly (DP-1) and quadratically (DP-2) anisotropic distributions of angular fluxes for calculations of transmission probabilities. Three approaches, subdivision of optically thick regions, expansion of collision sources and the diffusion approximation, have been developed and implemented to correct effects of the preferential probability of collided neutrals escaping back across the incident surface. Solving the diffusion equation via the finite element method has been shown to be the most computationally efficient and accurate for a broader range of D/l by comparisons with Monte Carlo simulations. The average neutral energy (ANE) approximation has been developed and implemented into the GTNEUT code. The average neutral energy approximation has been demonstrated to be more accurate than the original local ion temperature (LIT) approximation for optically thin regions. The simulations of the upgraded GTNEUT code excellently agree with the DEGAS predictions in DIII-D L-mode and H-mode discharges, and the results of both the codes are in a good agreement with the experimental measurements.


Fusion Plasma Physics

Fusion Plasma Physics

Author: Weston M. Stacey

Publisher: John Wiley & Sons

Published: 2012-10-15

Total Pages: 674

ISBN-13: 3527411348

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This revised and enlarged second edition of the popular textbook and reference contains comprehensive treatments of both the established foundations of magnetic fusion plasma physics and of the newly developing areas of active research. It concludes with a look ahead to fusion power reactors of the future. The well-established topics of fusion plasma physics -- basic plasma phenomena, Coulomb scattering, drifts of charged particles in magnetic and electric fields, plasma confinement by magnetic fields, kinetic and fluid collective plasma theories, plasma equilibria and flux surface geometry, plasma waves and instabilities, classical and neoclassical transport, plasma-materials interactions, radiation, etc. -- are fully developed from first principles through to the computational models employed in modern plasma physics. The new and emerging topics of fusion plasma physics research -- fluctuation-driven plasma transport and gyrokinetic/gyrofluid computational methodology, the physics of the divertor, neutral atom recycling and transport, impurity ion transport, the physics of the plasma edge (diffusive and non-diffusive transport, MARFEs, ELMs, the L-H transition, thermal-radiative instabilities, shear suppression of transport, velocity spin-up), etc. -- are comprehensively developed and related to the experimental evidence. Operational limits on the performance of future fusion reactors are developed from plasma physics and engineering constraints, and conceptual designs of future fusion power reactors are discussed.


Bulletin of the Atomic Scientists

Bulletin of the Atomic Scientists

Author:

Publisher:

Published: 1961-05

Total Pages: 88

ISBN-13:

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The Bulletin of the Atomic Scientists is the premier public resource on scientific and technological developments that impact global security. Founded by Manhattan Project Scientists, the Bulletin's iconic "Doomsday Clock" stimulates solutions for a safer world.


Columbia Crew Survival Investigation Report

Columbia Crew Survival Investigation Report

Author: Nasa

Publisher: PDQ Press

Published: 2009

Total Pages: 400

ISBN-13: 9780979828898

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NASA commissioned the Columbia Accident Investigation Board (CAIB) to conduct a thorough review of both the technical and the organizational causes of the loss of the Space Shuttle Columbia and her crew on February 1, 2003. The accident investigation that followed determined that a large piece of insulating foam from Columbia's external tank (ET) had come off during ascent and struck the leading edge of the left wing, causing critical damage. The damage was undetected during the mission. The Columbia accident was not survivable. After the Columbia Accident Investigation Board (CAIB) investigation regarding the cause of the accident was completed, further consideration produced the question of whether there were lessons to be learned about how to improve crew survival in the future. This investigation was performed with the belief that a comprehensive, respectful investigation could provide knowledge that can protect future crews in the worldwide community of human space flight. Additionally, in the course of the investigation, several areas of research were identified that could improve our understanding of both nominal space flight and future spacecraft accidents. This report is the first comprehensive, publicly available accident investigation report addressing crew survival for a human spacecraft mishap, and it provides key information for future crew survival investigations. The results of this investigation are intended to add meaning to the sacrifice of the crew's lives by making space flight safer for all future generations.


Plasma Physics

Plasma Physics

Author: Alexander Piel

Publisher: Springer

Published: 2018-05-18

Total Pages: 463

ISBN-13: 9783319875538

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The enlarged new edition of this textbook provides a comprehensive introduction to the basic processes in plasmas and demonstrates that the same fundamental concepts describe cold gas-discharge plasmas, space plasmas, and hot fusion plasmas. Starting from particle drifts in magnetic fields, the principles of magnetic confinement fusion are explained and compared with laser fusion. Collective processes are discussed in terms of plasma waves and instabilities. The concepts of plasma description by magnetohydrodynamics, kinetic theory, and particle simulation are stepwise introduced. Space charge effects in sheath regions, double layers and plasma diodes are given the necessary attention. The novel fundamental mechanisms of dusty plasmas are explored and integrated into the framework of conventional plasmas. The book concludes with a concise description of modern plasma discharges. Written by an internationally renowned researcher in experimental plasma physics, the text keeps the mathematical apparatus simple and emphasizes the underlying concepts. The guidelines of plasma physics are illustrated by a host of practical examples, preferentially from plasma diagnostics. There, Langmuir probe methods, laser interferometry, ionospheric sounding, Faraday rotation, and diagnostics of dusty plasmas are discussed. Though primarily addressing students in plasma physics, the book is easily accessible for researchers in neighboring disciplines, such as space science, astrophysics, material science, applied physics, and electrical engineering. This second edition has been thoroughly revised and contains substantially enlarged chapters on plasma diagnostics, dusty plasmas and plasma discharges. Probe techniques have been rearranged into basic theory and a host of practical examples for probe techniques in dc, rf, and space plasmas. New topics in dusty plasmas, such as plasma crystals, Yukawa balls, phase transitions and attractive forces have been adopted. The chapter on plasma discharges now contains a new section on conventional and high-power impulse magnetron sputtering. The recently discovered electrical asymmetry effect in capacitive rf-discharges is described. The text is based on an introductory course to plasma physics and advanced courses in plasma diagnostics, dusty plasmas, and plasma waves, which the author has taught at Kiel University for three decades. The pedagogical approach combines detailed explanations, a large number of illustrative figures, short summaries of the basics at the end of each chapter, and a selection of problems with detailed solutions.


Physics and Applications of Pseudosparks

Physics and Applications of Pseudosparks

Author: Martin A. Gundersen

Publisher: Springer

Published: 2012-10-18

Total Pages: 362

ISBN-13: 9781461366874

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The purpose of the 1989 NATO ARW was to develop applications, and an improved understanding of the physics for high current emission and conduction observed in hollow cathode-hollow anode switches including the pseudo spark and BLT. New applications include highly emissive cathodes for microwave devices, accelerators and free electron lasers, high power tubes, electron and ion beams, microlithography, accelerators, and other plasma devices. Recent research has produced a new generation of gas-phase plasma switches that are characterized by very high current emission and conduction while operating in a glow mode. These switches include the pseudospark and the BLT, both of which have hollow electrodes, switch over 10 to 100 kA peak current, and have cathodes with emission ~ 2 2 10,000 Ncm over ~ 1 cm area. The cathode properties are especially remarkable - about 2 orders of magnitude larger emission than existing thermionic cathodes. Part of the meeting was devoted to understanding these properties, and exploiting applications of this cathode. The remarkable properties of these switches are very surprising in the light of considerable previous work in this area, and these results deserve study in order to understand the underlying physical mechanisms, and to develop ideas and insight into future applications, and foster coherent research in this area. The operating cycle of pseudo-spark and BL T switches and related devices can be divided into four phases: hold-off, triggering, conduction, and recovery. There was very little discussion of the hold-off and recovery phases.